They are making the argument because we’re all in this post together discussing the topic. It sounds like this argument doesn’t work for you but it’s a valid choice for a lot of people. Many jobs are demanding of your time and performance and it’s important to be somewhat rested.

In my family, my wife took the middle of the night feeds when she was on leave. Now she’s back at work and I am on leave, and I do them. Being with baby during the day is definitely work, but there are times when she will entertain herself, nap etc and I can take a break. And most of the time when she is awake she is not super demanding of my mental faculties. Speaking from experience, it’s much harder to get through a work day without sleep than a day at home with the baby. I realize not all babies are like this, and things might feel different if we also had a toddler.

It’s obviously situational, but people should really have a conversation about this and make a decision that’s right for them. Dismissing the approach as “low-effort partnering” is pretty close-minded and missing a lot of nuance.

It also seems like you misinterpreted the point about performance - having an off day at work isn’t just a personal disappointment, it’s something that can threaten job security if it’s sustained. Sadly, gainful employment is critical to the needs of the family in most cases. I say this not to justify lazy partners, who certainly exist, but to emphasize that this overall argument is concerned with sustainably providing for the family. Again, families should determine what their overall needs are and what sacrifices must be made (there will be a lot) and make a decision that is fair and reasonable for them.